Fired heater



May 11, 1965 F. A. LEE ETAL FIRED HEATER Filed Feb. 19. 1963 3Sheets-Sheet 2 May 11, 1965 F. A. LEE ETAL FIRED HEATER 3 Sheets-Sheetl3 V Filed Feb.y 19. 1963 United States Patent O 3,132,636 EIRED HEATERFrank A. Lee, Westwood, NJ., Peter von Wiesenthal,

New York, N117., and Kenneth R. Wagner, .Iersey City,

NJ., assignors to Foster Wheeler Corporation, New

`tork, NX., a corporation of New York Filed Feb. 19, 1963, Ser. No.259,564 3 Claims. (Cl. 122-240) This application is acontinuation-in-part of application Serial No. 144,409, tiled Octoberl1, 1961, and now abandoned.

This invention relates to the heating of fluids. It is a fired heatersuitable for such uses as high temperature cracking of hydrocarbon oils,thermal polymerization of light hydrocarbons or hydrogenation of oils.

In giving physical realty to prescribed process conditions, it is oftennecessary to maintain iluids for specific periods of time at elevatedtemperatures. Space velocity is easily regulated by flow controls. Theprincipal problem is to tix a uniform high temperature about theperipheries and along the lengths of tubes. Attempts to employ tiredheaters in providing such reaction conditions have been confounded bylocal scorching of process streams, coke clogging and local tubedeterioration.

The present invention provides a novel heater design by which thedifficulty of non-uniform heat inux is overcome. More particularly, thisdesign contemplates the passage of process lluid through vertical tubespositioned medially between radiant refractory walls. Short flameburners inject llames into elongated troughs adjacent the side Walls tolill the troughs so that hot combustion gases spread to sweep the sidewalls affording uniform temperature of the radiation sources.Additionally, steep rims shield the tubes from direct impingement ofcombustion gases.

Basically this disclosure teaches a combination of features whichattains more uniform high tempera-ture. Tests have shown that thiscombination affords a temperature deviation of less than two percentover the radiant walls. With overlapping of radiation from the Walls -tothe tubes there is practically a constant heat availability to each ofthe tubes over its entire length between a pair of side walls.

In tired heaters various heat ux requirements often exist along the pathof the fluid. By the present design the intensity of heat flux in eachcell can be controlled independently of the intensities in other cellsso that each cell may be tired to yield a specific intensity for theconversion rate there desired. Additional advantages are derived fromthe use of floor burners.

Temperature difference between shut-down and fired conditions can giverise to expensive tube design and support diiculties. Accordingly, afurther advantage of this design resides in its reverse U-bend coplanarserpentine tube configuration. By this expedient, the tube, itself,serves as a multibend expansion joint. Inlet and outlet connections canbe fixed with all of the expansion of the tubes being absorbed byaccordion deflection of .the ser.- pentine tubes. Accordion deectionrelieves stresses which might otherwise be imposed on external piping.This feature eliminates the necessity for expensive tube supports tocontrol and direct ther-mal movements. The tubes may be simply suspendedin position. Vertical insertion and removal is accommodated. As afurther construction simplification, tubes in successive cells can beserially connected above the partitions.

These and other -advantages will appear more fully from the accompanyingdrawings wherein:

yFIGURE I is an end elevation view in section taken along line II ofFIGURE Il and showing a heater embodying the present advance.

F lce FIGURE II is a side elevation View in section taken along lineVII-II of FIGURE I.

FIGURE III is a fragmented isometric view of a portion of the heater anddepicts the relationship of burners, radiant side walls and tubes.

`FIGURE IV is an enlarged sectional View of a preferred type of floorburner.

FIGURE V is a sectional view taken along line V-V of FIGURE IV.

As shown in the drawings, a rectangular setting generally designated 1has oor 2 and roof 3. Partition means shown as longitudinal partition 4and transverse partitions 6 project upward from floor 2 to define aplurality of substantially rectangular cells 7. Longitudinal partition 4and longitudinal walls S of the setting are faced with refractory toprovide pairs of parallel refractory faced side walls oppositelydisposed each relative the other in the setting.

Floor 2 defines elongated troughs 9 adjacent and parallel to each ofthese side walls. Burners 11 Vare disposed to inject a short llame intoeach of the troughs 9. Burner nozzles 12 are elongated to provide alongitudinal projection parallel to each of the side walls. A pluralityof iiame openings 13 are provided so that ame substantially fillstroughs 9 with a major portion of the fuel combustion completed introughs 9. Hot combustion gases tend toward following the side wallspassing in sweeping relationship over substantially the entire surfaceof each side wall for heating the refractory to a uniform tempera-ture.

As best seen in FIGURES IV and V, fuel is conducted via pipes 14 toburners 11. Primary air enters at 16 and mixes with fuel in burnerchamber 17. Secondary air enters through ports 18 and passage 19 tosupport combustion of the fuel.

Vertical tubes 21 are mounted in a row between opposed pairs of sidewalls and are arranged to receive radiation 1from both of the associatedside walls over substantially the entire lengths of the tubestherebetween.

Steep rims 22 on the sides of troughs 9 adjacent tubes 21 divert the hotcombustion gases so that they do not directly -impinge onto tubes 21.

Flue means, comprising flue passage 23, communicate with each cell 7 forremoving products of combustion therefrom. Partitions 4 and 6 projectupward from floor 2 and have upper ends 24 and 26 respectively spacedfrom roof 3 to define common passage 27 communicating among cells 7.Flue passage 23 communicates with tine port 28 to exhaust combustionproducts from all of the cells '7 via common passage 27.

Process iluid is circula-ted serially through tubes 21 disposed in a rowapproximately midway between opposed side walls. As best shown in FIGUREII, each tube 21 is arranged in a coplanar serpentine configuration.Loops 29 pass over transverse partitions 6 to conneet tubes 21.Suspension means shown as straps 31 are connected between roof 3 and atleast one of the tubes 21 to support the tubes.

Preheat conduit 32 disposed in ilue passage 23 is connected in flowseries upstream of tubes 21 to preheat the process fluid.

As process fluid courses from cell to cell, the firing rates of burners11 in each cell 7 are controlled (by means well known in the heater art)so that heat flux in each cell 7 is maintained at a desired intensity.

It will be understood by those skilled in the fired heater art thatchanges may be made in the details of construction of this heaterWithout departing from this invention as defined in the claims.

What is claimed is:

l. A heater comprising a setting having a door,

aleaeae a partition defining a plurality of substantially rectangularcells in the setting,

means in each of the cells providing a pair of upright refractory facedside Walls oppositely disposed each relative the other,

trough means immediately adjacent, approximately coextensive, andparallel to each of the side walls along the bottom thereof,

a plurality of short burst flame burners disposed to inject flame intoeach of the troughs to fill the troughs so that hot combustion gasespass in sweeping relationship over substantially the entire surface ofeach of the side walls for heating the refractory to unform temperature,

a single row of aligned vertical tubes supported approximately midwaybetween said pairs of refractory faced side walls in each of said cells,

the tubes spaced apart sufliciently so that each receives radiationevenly around the periphery thereof from both of a pair of the sidewalls over substantially the entire length of the tube between the sidewalls,

each of the troughs having a steep rim on the side adjacent theassociated tube to divert the hot cornbustion gases so that they willnot impinge thereon,

means for coursing a process fluid through each of the tubes,

means connecting the tubes of separate cells in series,

a common ue communicating in flow series with each of the cells forexhausting products of combustion therefrom.

2. A heater comprising a rectangular setting having a Hoor and a roof,

at least one interior longitudinal wall projecting upward from thefloor,

at least one interior transverse wall projecting upward from the floor,

said walls and the setting defining at least two longitudinal rows ofcells in the setting,

each cell having a pair of side walls faced with refractory and disposedoppositely relative each other and trough means immediately adjacent,approximately coextensive and parallel to each of the side wallslongitudinally relative the setting,

a plurality of short burst flame burners disposed to inject flame intoeach 0f the troughs to ll the troughs so that hot combustion gases passin sweeping relationship over substantially the entire surface of eachof the side walls for heating the refractory to a uniform temperature,

each of the interior walls having an upper end spaced from the roof todefine a common passage cornmunicating among the cells,

a flue housing connected to the roof of the setting and defining a fluepassage,

the roof describing a flue port communicating the common passage withthe flue passage to exhaust products of combustion from all of the cellstherethrough,

a single row of aligned vertical tubes disposed in each of the cells andspaced approximately midway between a pair of opposite side walls,

each of the trough means having means on the side adjacent theassociated tubes to divert the hot combustion gases so that they willnot impinge thereon,

each of the tubes spaced apart sufficiently so that each receivesradiation evenly around the periphery thereof from both of the sidewalls over substantially the entire length of the tube between the sidewalls,

means connecting the tubes in each row of aligned tubes in flow series,

at least one of the tubes of each row of aligned tubes connectedserially with a tube in the next adjacent cell whereby a process fluidis passed in series through adjacent cells,

each row of aligned vertical tubes constituting a flow pass, theinterior walls permitting independent pass control.

3. A heater comprising a setting having a floor,

a partition means defining a plurality of substantially rectangularseparate cells within the setting, each of the cells including a pair ofupright refractory faced side walls oppositely disposed,

elongated trough means immediately adjacent, approximately coextensiveand parallel to each of the side walls along the bottom thereof,

a plurality of short burst llame burners disposed to inject flame intoeach of the troughs to fill the troughs so that hot combustion gasespass in sweeping relationship over substantially the entire surface ofeach of the side walls for heating the refractory to a uniform radiatingtemperature,

a single row of substantially aligned vertical tubes in each of thecells supported approximately midway between the side walls spaced apartsufficiently so that each receives evenly around the periphery thereofradiation from both of the side walls for substantially the entirelength of the tube between the side walls,

each of the trough means having means on the side adjacent theassociated tubes to divert the hot combustion gases so that they willnot impinge thereon,

means connecting the tubes of one cell in flow series with the tubes ofanother cell,

means for coursing a process fluid through the tubes,

the tubes in each cell constituting a process fluid pass whereby theseparation of cells permits independent pass control.

References Cited by the Examiner UNITED STATES PATENTS 2,456,786 12/48Kniel et al. 122-356 2,456,787 12/48 Kniel 122-356 2,625,916 l/53 Barnes122-240 2,625,918 l/53 Lumly 122-356 2,825,313 3/58 Born et al 122-3563,066,656 12/62 HenSet 122-356 60 ROBERT A. OLEARY, Primary Examiner.

KENNETH W. SPRAGUE, Examiner.

2. A HEATER COMPRISING A RECTANGULAR SETTING HAVING A FLOOR AND A ROOF,AT LEAST ONE INTERIOR LONGITUDINAL WALL PROJECTING UPWARD FROM THEFLOOR, AT LEAST ONE INTERIOR TRANSVERSE WALL PROJECTING UPWEARD FROM THEFLOOR, SAID WALLS AND THE SETTING DEFINING AT LEAST TWO LONGITUDINALROWS OF CELLS IN THE SETTING EACH CELL HAVING A PAIR OF SIDE WALLS FACEDWITH REFRACTORY AND DISPOSED OPPOSITELY RELATIVE EACH OTHER AND TROUGHMEANS IMMEDIATELY ADJACENT, APPROXIMATELY COEXTENSIVE AND PARALLEL TOEACH OF THE SIDE WALLS LONGITUDINALLY RELATIVE TO SETTING, A PLURALITYOF SHORT BURST FLAME BURNERS DISPOSED TO INJECT FLAME INTO EACH OF THETROUGHS TO FILL THE TROUGHS SO THAT HOT COMBUSTION GASES PASS INSWEEPING RELATIONSHIP OVER SUBSTANTIALLY THE ENTIRE SURFACE OF EACH OFTHE SIDE WALLS FOR HEATING THE REFRACTORY TO A UNIFORM TEMPERATURE, EACHOF THE INTERIOR WALLS HAVING AN UPPER END SPACED FROM THE ROOF TO DEFINEA COMMON PASSAGE COMMUNICATING AMONG THE CELLS, A FLUE HOUSING CONNECTEDTO THE ROOF OF THE SETTING AND DEFINING A FLUE PASSAGE, THE ROOFDESCRIBING A FLUE PORT COMMUNICATING THE COMMON PASSAGE WITH THE FLUEPASSAGE TO EXHAUST PRODUCTS OF COMBINATION FROM ALL OF THE CELLSTHERETHROUGH, A SINGLE ROW OF ALIGNED VERTICAL TUBES DISPOSED IN EACH OFTHE CELLS AND SPACED APPROXIMATELY MIDWAY BETWEEN A PAIR OF OPPOSITESIDE WALLS, EACH OF THE TROUGH MEANS HAVING MEANS ON THE SIDE ADJACENTTHE ASSOCIATED TUBES TO DIVERT THE HOT COMBUSTION GASES SO THAT THEYWILL NOT IMPINGE THEREON, EACH OF THE TUBES SPACED APART SUFFICIENTLY SOTHAT EACH RECEIVES RADIATION EVENLY AROUND THE PERIPHERY THEREOF FROMBOTH OF THE SIDE WALLS OVER SUBSTANTIALLY THE ENTIRE LENGTH OF THE TUBEBETWEEN THE SIDE WALLS, MEANS CONNECTING THE TUBES IN EACH ROW OFALIGNED TUBES IN FLOW SERIES, AT LEAST ONE OF THE TUBES OF EACH ROW OFALIGNED TUBES CONNECTED SERIALLY WITH A TUBE IN THE NEXT ADJACENT CELLWHEREBY A PROCESS FLUID IS PASSED IN SERIES THROUGH ADJACENT CELLS, EACHROW OF ALIGNED VERTICAL TUBES CONSTITUTING A FLOW PASS, THE INTERIORWALLS PERMITTING INDEPENDENCE PASS CONTROL.